Background. Herbal formula Modified Buzhong-Yiqi-Tang (MBYT) has been widely used for the treatment of functional constipation in East Asia, but its efficacy and safety are unclear. Methods. The study was to evaluate the efficacy and safety of MBYT for adult patients with functional constipation. Randomized clinical trials were selected according to predefined inclusion and exclusion criteria. Results. In total, twenty-five randomized controlled clinical trials were included with 2089 patients. There was evidence that MBYT treatment significantly improved the symptoms of functional constipation compared with stimulant laxatives, osmotic laxatives, and prokinetic agents. Our results also demonstrated that, when used as an adjuvant therapy, MBYT significantly improved the symptoms of functional constipation, when compared with osmotic laxatives alone, prokinetic agents alone, and biofeedback alone. Moreover, patients taking MBYT experienced fewer adverse events compared to the control groups. Conclusion. This review suggests that MBYT appears to have excellent therapeutic effect on adult patients with functional constipation and no serious side effects were identified. However, due to overall limited quality, the therapeutic benefit of MBYT may be substantiated to a limited degree. Better methodological quality and large controlled trials are expected to further quantify the therapeutic effect of MBYT.